An unusual thioredoxin system in the facultative parasite Acanthamoeba castellanii

摘要: The free-living amoeba Acanthamoeba castellanii occurs worldwide in soil and water feeds on bacteria other microorganisms. It is, however, also a facultative parasite can cause serious infections humans. annotated genome of A. (strain Neff) suggests the presence two different thioredoxin reductases (TrxR), which one is small bacterial type large vertebrate type. This combination highly unusual. Similar to TrxRases, gene coding for TrxR contains UGA stop codon at C-terminal active site, suggesting selenocysteine. We characterized system conjunction with glutathione reductase (GR), obtain more complete understanding redox roles its components response oxidative stress. Both TrxRases localize cytoplasm, whereas GR localizes cytoplasm organelle fraction. could only identify (Trx-1) be indeed reduced by i.e., TrxR. thioredoxin, turn, reduce peroxiredoxins tested methionine sulfoxide A (MsrA). Upon exposure hydrogen peroxide diamide, was upregulated expression mRNA protein levels, but not Our results show that involved castellanii’s role TrxR, remains elusive.